1. Field of the Invention
The present invention relates to a production method of bean curd, and an apparatus thereof.
2. Description of the Related Art
Nowadays bean curd capable of being stored in a frozen state (hereinafter referred to as "frozen bean curd") is known.
Production of the above-mentioned frozen bean curd is conducted in a batch processing method, that is, producing soybean milk in an ordinary method, accommodating the soybean milk in a container of a certain capacity, cooling, mixing with a thickener, and mixing with a solidifying agent. Then the mixture is heated to a certain temperature for maturing and solidification, and frozen as described in Japanese Unexamined Patent Publication No. 5-316984. Examples of the abovementioned thickeners include starch and gelatin. Examples of the above-mentioned solidifying agents include calcium sulfate.
Since the thickeners have a function of reducing the ratio of free water in the water content of the bean curd so as to increase the internal viscosity of the bean curd, separation and expansion of the water content generated at the time of freezing can be reduced, and thus the internal structure of the bean curd can be preferably maintained at the time of thawing.
The soybean milk needs to be cooled down to about 30.degree. C. when mixed with the thickener or the solidifying agent. This is because a high temperature of the soybean milk causes an excessively large viscosity of the thickener so that homogeneous mixing of the solidifying agent becomes extremely difficult, which may result in uneven quality of the bean curd.
In the above-mentioned conventional production method, the soybean milk, which has a high temperature of about 70 to 95.degree. C. immediately after the production thereof, should be cooled down to about 30.degree. C. for mixing with a thickener or a solidifying agent, and be heated to about 70 to 95.degree. C. again for the subsequent maturing and solidification, and thus it is extremely unreasonable in terms of heat utilization. Besides, since the conventional method is a batch processing method, it involves a problem of requiring a long production time. Furthermore, since mixing and stirring are conducted at a low temperature area, it involves another problem of the tendency of requiring a large amount of a thickener and a solidifying agent.
Accordingly, an object of the present invention is to provide a continuous production method of bean curd, and an apparatus thereof, capable of utilizing heat of the soybean milk reasonably, dramatically reducing the production time, and minimize the amount of the thickener and the solidifying agent.